DOS command "md" wipes out pre-existing directories ... sometimes

In a ReactOS (38223-rel) DOS window if I type this command:

md NewSubDirectory

...it works without any errors (because the directory is new). If I type the same command again immediately after:

md NewSubDirectory

...no error is generated. An error describing that a file or directory with the same name already exists instead of just returning to the prompt without any such indication.

Sometimes, the contents of the directory get deleted for other pre-existing directories when I use the "md" command – this should never happen.